where \(\mathbf {H}_{k,k}\in \mbox{$\mathbb {C}$}^{M_k\times N_k}\)  denotes the SI channel seen at the RX antennas of node \(k\)  due to its own DL transmission, \(\mathbf {H}_{k,m}\in \mbox{$\mathbb {C}$}^{M_k\times N_m}\)  is the UL channel gain matrix (i\(.\) e\(.\) , between nodes \(k\)  and \(m\) ), and \(\mathbf {n}_{k}\in \mbox{$\mathbb {C}$}^{M_k\times 1}\)  denotes the received AWGN at node \(k\)  with variance \(\sigma _{k}^{2}\) . The first term in (REF ) describes the residual SI signal after analog cancellation and A/D TX/RX beamforming, while its second term contains the A/D RX combined signal transmitted from node \(m\)  plus AWGN. In contrast to [1]}, \(k\)  needs to cancel the SI channel \((\mathbf {U}_k^{(\mathrm {RF})})^{\rm H}\mathbf {H}_{k,k}k^{(\mathrm {RF})}\) , which is a matrix of dimension \(M_k^{\mathrm {(RF)}}\times N_k^{\mathrm {(RF)}}\)  and not the actual \(M_k\times N_k\)  SI channel \(\mathbf {H}_{k,k}\) .
